You can make them with the camo burlap or surplus camo netting and tie it between trees, fencepost or even to dead fall. If you prefer4 pieces of angle iron for posts then tie strap the material to the angle iron. You'll need to leave 12-18" of angle iron below the material to pound into the ground. Spruce it up with natural cover such as branches, etc. I make natural ground blinds out of logs or deadfall then add branchs or better yet spruce balms to the logs for more cover. Burlap or camo netting would also work on the inside of the logs or deadfall.
With that said I have invested in a few pops blinds that work very well and are extremely easy to setup. Not the best out their but have served the purpose for me for the last few years. Mine are the ameristep doghouse (picture below) and you should be able to find them on ebay pretty reasonably.
For a more permanent setup I build box blinds with 2x4 frame and then wrap them in carpet (juteback out). I get the carpet from carpet installers and wood from my bro in law from demo jobs (contractor) at no charge. My costs are a few cans of spray paint for the juteback/camo paint job and hardware items - very cheap. Problem is they are not portable at all!